Leviticus 16:23-25

And Aaron shall come into the tabernacle of the congregation, and shall put off the linen garments, which he put on when he went into the holy place, and shall leave them there:

And he shall wash his flesh with water in the holy place, and put on his garments, and come forth, and offer his burnt offering, and the burnt offering of the people, and make an atonement for himself, and for the people.

And the fat of the sin offering shall he burn upon the altar.